Diagnostic criteria for diabetic nephropathy 1. A definite history of diabetes mellitus. 2.Urinary albumin excretion rate (UAER): If the UAER is between 20-200?g/min (28.8-288mg/24h) for three consecutive urine tests within 3 months and other causes of increased UAER can be excluded, early diabetic nephropathy can be diagnosed. 3, persistent proteinuria: urine protein >0.5g/24h for more than 2 times in a row, and can exclude other causes of increased urine protein, can be diagnosed as clinical stage diabetic nephropathy. Clinically, diabetic nephropathy should be considered in all diabetic patients with abnormally high urinary albumin excretion rate and urinary protein quantification, or with edema, hypertension, renal function impairment, or with diabetic retinopathy. Attention should also be paid to exclude urinary tract infections and a variety of primary and secondary renal diseases as well as heart failure and hypertension as causes of increased urinary albumin excretion rate and urinary protein. Staging of diabetic nephropathy Stage I: increased glomerular filtration rate, increased kidney volume, no albumin in urine, no pathological histological damage. Renal blood flow, glomerular capillary perfusion and internal pressure are increased, and its initial changes are reversible． Stage II: Normal albuminuria stage. The urinary albumin excretion rate (UAER) is normal, the GBM is thickened, the thylakoid matrix is increased, and the GFR is mostly higher than normal. Stage III: Early diabetic nephropathy. The urinary albumin excretion rate (UAER) was 20-200?g/min or 30-300 mg/24 h. The GBM was thickened, the thylakoid matrix increased significantly, glomerular nodular and diffuse lesions and small arterial vitreous lesions appeared, and glomerular wasting began to appear. Stage IV: clinical diabetic nephropathy or overt diabetic nephropathy, UAER persists at 200?g/min or urine protein >0.5g/24h, blood pressure is increased, edema appears. Glomerular wasting is evident and GFR begins to decline. Stage V: end-stage renal failure (uremia). gfr<10ml/min. extensive glomerular wasting, increased blood creatinine and urea nitrogen, with severe hypertension, hypoproteinemia and edema.